The present invention relates to a thermoplastic resin composition, more particularly relates to a thermoplastic resin of which the molded articles show good plate adhesion to their surfaces, and also have excellent coating properties and improved impact resistance.
The molded articles of rubber-reinforced thermoplastic resins such as ABS resins are often subjected to secondary works such as plating, coating, sputtering, ion plating, etc. Particularly, in the case of plating, if a molded article is simply plated, there may not be obtained sufficient adhesive strength between the deposit and the surface of the molded article, so that the deposit releases easily from the surface in use. For enhancing adhesive strength of the deposit, a method is known in which the surface of the molded article to be plated is subject to an oxidation treatment to decompose rubber material present in the molded article surface layer and then the article surface is etched to form fine indents, after which plating is conducted. According to this method, it is supposed possible to enhance adhesive strength of the deposit by anchor effect because the deposit bites into the indents. Practically, however, such fine indents formed by etching are deformed during plating, and the desired adhesive strength can not be obtained.
Further, there is a problem that by the etching the mechanical strength, particularly impact resistance of the molded articles is deteriorated. Thus, there is a demand to provide a resin composition having a good balance of plate adhesion and mechanical properties when processed into a molded article.
Further, in coating of the articles molded from conventional rubber-reinforced thermoplastic resins such as ABS resins, there is a problem of improper adhesion of the coating film, color shading of the coated surface due to suction of the thinner into the molded article and consequent impairment of its visual appearance.
As a result of the present inventors' earnest study to solve the above problem, it has been found that the articles molded from a rubber-reinforced thermoplastic resin composition having a specific ratio of weight-average molecular weight Mw to number-average molecular weight Mn of the acetone soluble matter (Mw/Mn ratio) and a specific ratio of Z-average molecular weight MZ to number-average molecular weight Mn of the acetone soluble matter (MZ/Mn ratio) show good plate adhesion on their surface and also have excellent coating properties and mechanical strength, typically impact resistance. The present invention has been attained on the basis of the above findings.